1. Technical Field
The present invention relates generally to a content protection apparatus and method using the binding of additional information to an encryption key and, more particularly, to a content protection apparatus and method, which bind additional information required to check integrity (to determine whether forgery has occurred) to an encryption key used to encrypt content and provide a user with bound result data, thus enabling the application of a technique for performing decryption while checking the integrity of the encryption key and the additional information.
2. Description of the Related Art
Digital Rights Management (DRM) technology used to distribute and protect digital content is implemented to encrypt content and transmit both a content encryption key and content authority information to each user terminal using a method whereby only the proper recipient is allowed to decipher the content encryption key and the content authority information in order to protect the rights of content providers.
An existing encryption mechanism is configured to externally receive an encryption key and encrypt plain text into cipher text or configured to receive cipher text and an encryption key as input and perform decryption. However, most software can detect an encryption calculation procedure and all intermediate values via a software analysis attack such as that of a debugger, and can decipher and infer the encryption key.
White-box cryptography is a new encryption technique which represents such an encryption mechanism by a large look-up table and conceals encryption keys in the look-up table, thus making it impossible to infer which key is an actual encryption key even if an attacker monitors encryption key processing. This technique was disclosed in the thesis entitled “White-Box Cryptography and an AES Implementation” by S. Chow, P. Eisen, H. Johnson, P. C. van Oorschot in Proc. of the 9th Annual Workshop on Selected Areas in Cryptography in 2002.
Meanwhile, in the case of existing DRM systems, when the copyright of content is protected, the content is encrypted, and an encryption key used therein is separately transferred with the encryption key included in authority information. As a result, a problem may arise in that the authority information included in the software of a hackable terminal or stored in a specific area of the terminal may be divulged and illegally reused on other platforms.